trong>Narrator: This is Science Today. Researchers at the University of California, San Francisco are looking at how molecules that regulate pain signaling change with age. Pamela Pierce Palmer, director of the Pain Management Center says their study was the first of its kind.

Palmer: We actually studied many, many areas of the brain and looked at a very specific protein called RGS proteins. And RGS9 is one of the hot new proteins that are involved in morphine signaling and so no one had ever looked at age in RGS9 expression.

Narrator: The researchers discovered that young rats experienced drug tolerance more than five times sooner than the oldest rats. These findings were consistent with human studies in which older patients had long-term benefit from opioid medication, while younger patients did not.

Palmer: We're excited basically to be pushing forward this idea of let's find the underlying basis of these age-related differences because if we can do that, the ultimate goal is how we can trick maybe a young neuron into thinking it's old when it comes to opiates.

Narrator: For Science Today, I'm Larissa Branin.